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Re: Copper Banding?



Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>

Tesla list wrote:
Original poster: Kurt Schraner <k.schraner@xxxxxxxxxxx>
Hi David, Scott D,
well, the effect is _real_, and not a matter of words only. Let me remind a former posting, where a comparison of measured vs. calculated L values has been shown, at:
http://www.pupman.com/listarchives/2004/October/msg00018.html
I didn't yet get an answer, explaining in easy to understand physical reasoning, about the difference. Might be, it can be interpreted, by way of a higher interturn capacitance in ribbon primaries, than "wire" spirals of the same planar geometry, counteracting the inductance?
Regards,
Kurt Schraner
Tesla list schrieb:


Original poster: "david baehr" <dfb25@xxxxxxxxxxx>

In a previouse post, it was stated that a banded pri. would have less inductance than a copper tubing pri. Could someone explain this ? IF YA got 50' of copper tubing , and 50' of banded pri. , wouldnt be about the same ????????////

The reason is that a flat spiral made with tape acts as a stack of coupled filamental coils. If the coupling were unitary, the inductance
would be the same of a single filament. But as the coupling between distant filaments is smaller than one, the inductance decreases.
Consider for example two parallel filamental coils with inductance L.
If they are at small distance, they act as a single coil with inductance
L. If they are far apart, the coupling between them is insignificant,
and the total inductance falls to L/2.


Antonio Carlos M. de Queiroz